What's the best way to find out if someone likes you without being obvious?

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So, I really like one of my friends and lately he's been extra sweet. I want to find out if he likes me and possibly pursue a relationship, but I don't won't to make things awkward by just asking him. The reason I'm not sure is cause he's a big flirt and so I don't know whether or not the things he says to me he also says to other girls. What's a good way to find out without just saying, "Hey, do you like me?" Thanks!